The rationale for this application is to allow Dr. Riann Palmieri-Smith to receive both the didactic training and practical research experience necessary for her evolution into an independent clinical research scientist. This award will provide her with an opportunity to complete coursework in the areas of biomechanics and clinical research design. Dr. Palmieri-Smith will conduct clinical research, under the direction of Drs. Ashton-Miller, Sowers, and Wojtys examining the impact of quadriceps inhibition on knee mechanics and will also examine the feasibility of introducing neuromuscular electrical stimulation (NMES) as an adjunct to ACL rehabilitation. Building on the experience gathered during the period of this award, Dr. Palmieri-Smith will use the information she obtains from mechanistic, laboratory-based studies to develop and test clinical interventions that can improve the neuromuscular and functional recovery of persons following traumatic knee joint injury and those with osteoarthritis. The proposed research will determine the magnitude of quadriceps inhibition necessary to result in biomechanical, functional, and neuromuscular adaptations, and the feasibility of introducing NMES, an intervention capable of restoring quadriceps activation, in rehabilitation post-ACL reconstruction to restore normal mechanics. The burst superimposition technique will be utilized in subsets of ACL reconstructed patients to estimate quadriceps inhibition prior to and following ACL reconstruction and prior to and following NMES. Mechanics will be examined during a onelegged forward hop. RELEVANCE: Quadriceps inhibition is present following ACL injury and reconstruction and often persists for years following repair and its consequences remain elusive. Our work will allow for a better understanding of how muscle dysfunction impacts joint protective mechanisms. Introducing NMES as an adjunct to ACL rehabilitation may promote sustained improvements in quadriceps activation thereby restoring lower extremity mechanics and potentially reducing the incidence of post-traumatic osteoarthritis. This knowledge will aid clinicians in designing appropriate rehabilitation protocols and return to play guidelines that will prevent future injury and joint degeneration. [unreadable] [unreadable] [unreadable] [unreadable]